But local people always knew the answers

Forty years ago Mexico’s monarch butterfly winter mirabilia were known only to those who lived among them. Campesinos who celebrate their arrival in late autumn, wondered where the billions of magical beings went every spring when the dense clusters separated into individual butterflies, flew off high mountain trees, and disappeared. Forty years ago, people in the U.S. and Canada wondered what happened to the orange and black skydancers when they lifted into the air and left every autumn.

Forty-one years ago both mysteries connected and in August 1976 the zoologist behind this effort published an answer, but withheld specific location details. As we know now, summer’s last monarchs fly south, leaving their northern homes, funneling into a stream to fly across the border and down the Sierra Madre mountains to over-wintering sites in Mexico.*

It’s a clever mystery story. Answers to these questions are widely known but the people holding the information aren’t talking to each other. No one is asking the right people the right questions. The answer is hiding in plain sight if you know where to look. There’s no secret to discover, just information to gather and put together. Ultimately, it was the monarchs themselves, sent to zoologist Dr. Fred Urquhart, who connected both ends of the mystery. And even he maintained the monarch’s secrets.

Beginning in 1937, Urquhart and his wife Norah designed and affixed increasingly durable and sticky labels to the wings of monarchs in their summer range east of the Rockies. The labels read “Send to Zoology University Toronto Canada.” By 1971, hundreds of thousands of summer-range monarchs had been labelled by volunteers and tagged specimens were returned from myriad North American locales, including Mexico. The labelled monarchs sent to Urquhart mapped a distinct movement pattern from northeast to southwest, through Texas, and then into Mexico. So, in late 1972 Urquhart placed an ad in a Mexican newspaper asking for help tracking down exactly where in Mexico the monarchs ended their migration.

Kenneth Brugger, a U.S. citizen in Mexico City, answered the ad in early 1973 and began searching areas where labelled monarchs had been found. In April 1974, Brugger saw monarchs scattering in the sky as if from a central location and focused his attention in this area. Before finding the monarchs, Brugger met and married Catalina Trail, who was born on a ranch in Michoacán. And together they travelled in a motor home through the rugged Sierra Madre mountains searching for over-wintering monarchs.

Our summer monarchs (from east of the Rockies) taking their winter vacation on a white pine tree in Mexico.(Photo: Homero Gómez González)

The Xerces Society’s map of monarch migration corridors was possible after the 1975-76 discovery of their overwintering sites in Mexico.

Forty-one years ago in early January 1975, Trail and Brugger found the first monarch site in an oyamel fir forest at 10,000 feet on Cerro Pelon in northern Michoacán. A few days later they located two other colonies at El Rosario and Chincua. On January 9, 1975, they telephoned Urquhart and told him of their findings. Urquhart asked them to keep the news secret until he and Norah could visit and write a scientific announcement, but health problems postponed their visit for nearly a year. And, when Urquhart did release the news in an August 1976 National Geographic cover article, he didn’t reveal the exact locations.

The news was stunning! Scientists and the general public were thrilled by the “discovery.” Two lepidopterists who also studied monarchs, Dr. Lincoln Brower (whose chemical studies of monarchs identified the toxic benefits of their milkweed host plant) and Dr. William Calvert determined to locate the colonies for themselves.+ They asked Urquhart where the monarchs had been found and were told it was the Gulf Coast of Florida.

Sneaky scientist.

Some monarchs do overwinter on Florida’s Gulf Coast and off-shore islands, but these were not the butterflies they were seeking and did not account for the migration pattern to the southwest and into Mexico.

Brower and Calvert deciphered clues from Urquhart’s National Geographic article and a paper he published in a professional journal: the colonies were at 3,000 meters elevation, among oyamel fir, on volcanic mountain slopes in northern Michoacán, Mexico. This directed their search to an area west of Mexico City that met these criteria.

Calvert asked John Christian, a Spanish-speaking photographer who grew up in Mexico, to join the adventure, and together Calvert and Christian traveled to Mexico in a pickup truck. Christian handled translation and photography.

When they arrived in the small Michoacán town of Anganguea, they asked the Mayor’s son for help. The son was astonished anyone would be interested in the marvelous but commonplace seasonal phenomenon. And on New Year’s Eve 1976, Calvert and Christian found the El Rosario overwintering site one year after Trail and Brugger had first located it for Urquhart.

Now, forty-one years later, El Rosario, one of the monarch’s overwintering sites protected in the UNESCO Monarch Butterfly Biosphere Reserve, is open to the public. This season’s monarch population, how local residents are working to ensure their conservation and promote ecotourism, and on-going threats from logging and habitat destruction were described in a previous Daily Kos article Monarch Magic at El Rosario Sanctuary (photos!).

El Rosario is one of eight monarch colonies protected by the Biosphere Reserve, and is largest of the five that are open to the public. Six additional colonies occur outside the Reserve. The Biosphere is located in the states of Mexico and Michoacán in central Mexico. It includes 138,379 acres of oak-pine-fir forest habitat but monarchs occupy only a fraction of the reserve (0.67 acres total among all sites in 2013-2014), the rest is intended to protect the overwintering sites.

How you can help monarchs in their summer range by planting the right milkweed species for your area was presented in Sleeping milkweeds wait for spring monarchs. The last chapter of my story will discuss why monarch’s choose these overwintering habitats, what are the threats to their survival in their summer range, and mitigations for these threats.

SUPPORT MILLIONS OF MONARCHS AND THOUSANDS OF LOCAL PEOPLE BY VISITING EL ROSARIO MONARCH SANCTUARY IN MICHOACÁN, MÉXICO.